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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Performance of TRVs
Has anybody got any figures on the performance of Thermostatic Room Valves?
Settings 0 - 5 = ??? degrees C open to closed = ??? degrees C There must be a specification somewhere. Leaving my digital probe thermometer in one position in a room is giving me a swing of a few degrees in temperature, and I would like to chase down the reason for this differential. --- Dave Fawthrop dave hyphenologist co uk 20,000 free e-books at Project Gutenberg! http://www.gutenberg.org For Yorkshire Dialect go to www.hyphenologist.co.uk/songs/ also PG Nos 2888, 3232, 17472, 17799 |
#2
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Performance of TRVs
"Dave Fawthrop" wrote in message ... Has anybody got any figures on the performance of Thermostatic Room Valves? Settings 0 - 5 = ??? degrees C open to closed = ??? degrees C There must be a specification somewhere. Leaving my digital probe thermometer in one position in a room is giving me a swing of a few degrees in temperature, and I would like to chase down the reason for this differential. Because themostats generally do not open and close at the same temperature. Even when hysteresis defeating mechanisms are employed it is rare and proabably confined to purely solid state devices. Certainly a TRV is never going to perform in this way. -- Mike W |
#3
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Performance of TRVs
On Sun, 04 Feb 2007 21:17:20 +0000, Dave Fawthrop
wrote: Has anybody got any figures on the performance of Thermostatic Room Valves? Settings 0 - 5 = ??? degrees C open to closed = ??? degrees C There must be a specification somewhere. Leaving my digital probe thermometer in one position in a room is giving me a swing of a few degrees in temperature, and I would like to chase down the reason for this differential. --- It varies too much from make to make and unit to unit. Identical TRVs here have slightly different characteristics. |
#4
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Performance of TRVs
In article ,
Dave Fawthrop writes: Has anybody got any figures on the performance of Thermostatic Room Valves? Settings 0 - 5 = ??? degrees C open to closed = ??? degrees C There must be a specification somewhere. On a small sheet of paper in the box they came in. Leaving my digital probe thermometer in one position in a room is giving me a swing of a few degrees in temperature, and I would like to chase down the reason for this differential. Try measuring the temperature right next to the TRV head. The TRV can't do better than keeping that constant. -- Andrew Gabriel [email address is not usable -- followup in the newsgroup] |
#5
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Performance of TRVs
In an earlier contribution to this discussion,
Andrew Gabriel wrote: Try measuring the temperature right next to the TRV head. The TRV can't do better than keeping that constant. It can't even do that under all conditions. A given knob setting and room temperature will result in a particular flow restriction. But the *required* flow restriction to maintain a constant room temperature will vary, depending on the heat losses (heavily influenced by outside temperature) and on pump pressure - which will depend on what all the other TRVs in the system are doing. At best, TRVs can only provide crude temperature control. -- Cheers, Roger ______ Email address maintained for newsgroup use only, and not regularly monitored.. Messages sent to it may not be read for several weeks. PLEASE REPLY TO NEWSGROUP! |
#6
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Performance of TRVs
On Feb 4, 9:17 pm, Dave Fawthrop
wrote: Has anybody got any figures on the performance of Thermostatic Room Valves? Settings 0 - 5 = ??? degrees C open to closed = ??? degrees C There must be a specification somewhere. Danfoss RAS-C leaflet says; frost * 8 I 12 II 16 III 20 IIII 24 I C I don't think there is a standard. You won't get precise control throughout the room because, even if the TRV were operating perfectly, it would take some time for a change in output to be measureable at all points in the room. It's cheap & cheerful but good enough for most purposes. To get exact control of room temperature, you'd need to circulate something like 10 AC/hr through a convector heater. Even then, people's perception of comfort involves both humidity & radiant heat, as well as air temperature. E.G., the kids complain they're cold in the morning despite room air temperature being 21, 'cos floors and walls are cold. Kids are warm in the evening at the same air temperature 'cos floors & walls have heated up & so less heat lost through radiation. |
#7
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Performance of TRVs
On Sun, 04 Feb 2007 21:17:20 +0000, Dave Fawthrop wrote:
Has anybody got any figures on the performance of Thermostatic Room Valves? Settings 0 - 5 = ??? degrees C open to closed = ??? degrees C There must be a specification somewhere. Leaving my digital probe thermometer in one position in a room is giving me a swing of a few degrees in temperature, and I would like to chase down the reason for this differential. --- They are not made well enough and combined with other factors there is too much variation between units. Hence the relative scale using numbers, final user tweaking is needed to get the settings right. -- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at http://www.diyfaq.org.uk Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards |
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